Here is a pic of the front fork of our Co-Motion Speedster. The tire is a 28mm GatorSkin. The clearance is just about 3/8".
Is this enough info to ask if a 32mm or a 35mm Schwalbe Marathon Supreme will fit? Will also be using a fender.

I was all excited to try the Supremes last season, but we were quite disappointed with the ride. Both of us thought they felt slow/mushy. We were using 32mm rear and 28mm front. You might want to give them a test before committing to a big euro tour. Looks like enough room for a 32, maybe even with a tightly mounted fender, depending on mount.

It looks like it's pretty tight to accommodate a 32mm tire and a fender. I'd say one or the other, but not both.

Heh - we crossed in the ether. I had written essentially those words, but then expanded the pic and decided it looked maybe big enough with a tight mount. Anyway, there is no excess space there if you go with 32s.